1. Field of the Invention
The invention concerns a process for shaping an exposed end of a relatively low-melting cosmetic stick.
2. The Related Art
Deodorants, antiperspirants and lipsticks have the common characteristic of being composed of a solid low-melting waxy material encased in a suitable container provided with a means for urging the stick upwards through the container to expose more surface area as the stick is consumed. Deodorant and antiperspirant compositions generally have been fabricated by pouring the composition in molten state into the suitable container equipped with a twist-up device.
Top filling of the containers has been described in a number of patents including U.S. Pat. No. 2,818,167 (McKinley), U.S. Pat. No. 2,980,246 (Leshin), U.S. Pat. No. 3,907,441 (Idec), U.S. Pat. No. 4,232,977 (Chutter), U.S. Pat. No. 4,363,560 (Gentile), U.S. Pat. No. 4,521,127 (Tomburo et al) and U.S. Pat. No. 4,580,920 (Schmidt).
More recently, advantages have been shown with a bottom-filling technique. After filling is completed, but before solidification of the material to be dispensed, the twist-up mechanism is installed. Examples of this technology include U.S. Pat. No. 4,552,161 (Hill et al), U.S. Pat. No. 4,595,124 (Duval et al), U.S. Pat. No. 4,621,935 (Sussman), U.S. Pat. No. 4,664,547 (Rosenwinkle), U.S. Pat. No. 4,700,448 (Parker) and U.S. Pat. No. 4,702,399 (Davis). Filling solid stick dispensers before they are completely assembled and then subsequently completing assembly has been reported in U.S. Pat. No. 4,298,036 (Horvath), U.S. Pat. No. 4,545,696 (Carluccio), U.S. Pat. No. 4,605,330 (Crowley et al) and U.S. Pat. No. 4,915,528 (Seager).
A general problem with all the foregoing methods is need for a means to achieve a particular shape for the exposed end portion of the stick. Two techniques to accomplish the stick end shaping are mechanical trimming and molding procedures. Typical of mechanical trimming is EP 0 335 112 (Karavadra) wherein a solid antiperspirant stick is sculpted with a set of heated cutting edges. A pre-cut cutting edge is oscillated in one direction to partially cut into one side of the exposed end of the stick. Rough cut and finish cut cutting edges are then arcuately passed through the end of the stick in the opposite direction. U.S. Pat. No. 4,841,826 (Smith) trims by notching a deodorant bar on one side and a rough cutter moves inwardly through the other side of the body to enter the closed end of the notch and sever body material without breaking. Thereafter a finish cutter removes relatively little material to produce a finish cut.
Mechanical trimming has a major drawback in that there is significant material loss. There is also constraint on flexibility in the trim shape. Designs such as product trademark logos are quite difficult, if not impossible, to achieve with a trimming process. Finally, there is the detriment of low speed. Several trimming machines are, therefore, necessary if high unit volume is to be achieved.
Molding techniques have certain advantages over trimming. U.S. Pat. No. 4,369,158 (Woodruff et al) describes a process wherein a pouring cup is attached to the top of the container in a removable manner. Molten antiperspirant composition is injected through the bottom of the container. A twist-up device having air vents is then inserted into the still molten composition. Once cooled, the pouring cap, operating as a mold to achieve a domed shape on the exposed stick end, is thereafter removed. Among the problems of this method is the necessity for maintaining a molten state after the dome formation to accommodate insertion of the twist-up device. Additional costs are incurred because of this hot insertion. Production line speeds are also adversely impacted by the need to maintain the molten state for insertion of the twist-up device.
Accordingly, it is an object of the present invention to provide a process for manufacturing a cosmetic stick which avoids loss of any material during shaping.
It is another object of the present invention to provide a process for manufacturing a cosmetic stick of domed structure which allows for high speed shaping.
It is still another object of the present invention to provide a process for manufacturing a cosmetic stick which allows embossing of a design or logo onto an end thereof.
It is a further object of the present invention to obtain a cosmetic stick operative as a deodorant or antiperspirant and being provided through the process with a domed appearance with highly defined features.
A still further object of the present invention is to avoid use of a pouring cap necessary in previous molding processes and through its elimination avoid costs and drawbacks of this additional packaging component.
These and other objects of the present invention will become more readily apparent through consideration of the embodiments that follows.